Influence of gravity on a granular Maxwell’s demon experiment

In the usual description of the granular Maxwell’s demon experiment, where phase separation occurs due to an instability in the densities, the control parameter scales linearly with gravity. In this paper we investigate this scaling experimentally using the properties of diamagnetic particles in str...

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Bibliographic Details
Published in:The European physical journal. E, Soft matter and biological physics Soft matter and biological physics, 2009-02, Vol.28 (2), p.205-210
Main Authors: Isert, N., Maaß, C. C., Aegerter, C. M.
Format: Article
Language:English
Subjects:
Biological and Medical Physics
Biophysics
Classical statistical mechanics
Complex Fluids and Microfluidics
Complex Systems
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Granular solids
Kinetic theory
Material form
Nanotechnology
Physics
Physics and Astronomy
Polymer Sciences
Regular Article
Rheology
Soft and Granular Matter
Statistical physics, thermodynamics, and nonlinear dynamical systems
Surfaces and Interfaces
Thin Films
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Summary:In the usual description of the granular Maxwell’s demon experiment, where phase separation occurs due to an instability in the densities, the control parameter scales linearly with gravity. In this paper we investigate this scaling experimentally using the properties of diamagnetic particles in strong magnetic-field gradients to reduce and even balance gravitation. We find that phase separation occurs even at vanishingly small gravitational accelerations as is predicted by other theories. This is due to the fact that granular samples tend to form clusters as a result of the inelasticity of the particle collisions. Combining the heat balance of the driven granular gas with the cooling rate and thus the appearance of clustering, we are able to describe the crossover between the limiting cases.
ISSN:1292-8941
1292-895X
DOI:10.1140/epje/i2008-10403-7